Donald Trump has parted ways with his campaign manager and close ally, Corey Lewandowski.

The move appears to be a reaction to the presumptive GOP nominee's sagging poll numbers and weeks of difficulty as he prepped for a tough general-election fight with Hillary Clinton.

Hours after his abrupt exit, Lewandowski gave a pair of television interviews in which he put a positive spin on his exit.

"I wouldn't change one second of my time with Mr. Trump other than to say thank you, it's been an honor," the usually brash Lewandowski told MSNBC in brief comments.

In a nearly 30 minute interview with CNN's Dana Bash, Lewandowski said he didn't "know the answer" to why he was fired, but instead pointed to their record successes in the GOP primary campaign.

Later on Monday, there was a resignation from the campaign's staff preparing for the Republican National Convention. Michael Caputo, director of communications for caucus operations at the convention, quit after tweeting a message mocking Lewandowski's firing. "Ding dong the witch is dead!" Caputo tweeted, with a photo of the ruby slippers on the feet of the Wicked Witch of the East from The Wizard of Oz after she was crushed by a house.

"Unforced errors have no place on a general election campaign for the White House," Caputo said in a statement to NPR.

While some campaign sources tell NPR Trump's split with Corey Lewandowski was "mutual," another described it as a "firing" and a "summary execution." The source said the news was unwelcome for Lewandowski at the weekly Monday staff meeting. The "weekly Monday morning family meeting went awry for Corey," the source said.

Officially, the campaign tried to put a good face on it. "The Donald J. Trump Campaign for President, which has set a historic record in the Republican primary having received almost 14 million votes, has today announced that Corey Lewandowski will no longer be working with the campaign," spokeswoman Hope Hicks said in a statement. "The campaign is grateful to Corey for his hard work and dedication and we wish him the best in the future."

Lewandowski has been with Trump since he began his presidential run, managing his shoestring operation. But as Trump has moved into the general election, a more traditional campaign structure largely managed by Paul Manafort, a former Ronald Reagan aide, has emerged. Within the campaign, Manafort and Lewandowski have been seen as competing forces. A campaign source told NPR that Trump previously had liked the competitiveness between the two.

"[Corey] knew there was a battle brewing. I am certain he thought he would win," one campaign source told NPR.

In his interview with CNN, Lewandowski denied any tensions between the two, telling Bash that, "Paul and I have been getting along amazingly well."

Lewandowski said he would remain a Trump delegate from New Hampshire and would continue to work to help him beat Clinton in whatever way he could and was leaving with no "professional" regrets.

The now-former campaign manager, though, has been a source of controversy himself. There were accusations — and a battery charge that was later dropped — following a confrontation with a former reporter for Breitbart News in which Lewandowski was seen on video appearing to grab her arm. The news of his ouster on Monday was first reported by the New York Times.

Trump stood behind Lewandowski amidst those charges at a time when his ouster would have been a given for any traditional campaign. But CNN reported Monday that the breaking point appeared to have been growing tensions between himself and Trump's daughter, Ivanka, and son-in-law, Jared Kushner. Sources confirmed to NPR that Kushner was indeed playing a bigger role in the campaign. Lewandowski told CNN's Bash that he had a good relationship with all of Trump's family.

Instead, Trump has continued to swirl in controversy, targeting a judge presiding over the Trump University fraud case by accusing him of bias because of his Mexican heritage. He doubled down on his Muslim immigration ban and expanded it after last week's deadly shooting at a gay nightclub in Orlando, Fla. He called for a ban on anyone coming to the U.S. from any country with a proven history of terrorism against the U.S. or its allies. He also made confusing comments on guns, initially saying that if clubgoers had been armed, the shooter could have been stopped. He walked that back after even the NRA disagreed with him.

Lewandowski helped preside over Trump's unconventional primary campaign, bolstered by the billionaire businessman's sheer personality and ability to command the news cycles, dwarfing his GOP opponents. But in a general election, Trump hasn't been able to do the same.

Manafort was brought on earlier this year to help professionalize the skeletal, disorganized Trump operation. But there was reportedly tension between the two, with Lewandowski wanting to keep the same approach that had worked before, while Manafort worked to make Trump pivot to a more disciplined general-election approach.

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AUDIE CORNISH, HOST:

When it became clear that Donald Trump would be the Republican nominee for president, there were supporters who predicted that he would tone down his inflammatory rhetoric, the Republicans who hoped he would act more like a conventional politician. Well, that hasn't happened. But today, Trump did make one big change. He fired his original campaign manager, Corey Lewandowski. NPR's Sarah McCammon is covering the Trump campaign. And Sarah, to begin, why was Lewandowski kicked out?

SARAH MCCAMMON, BYLINE: You know, Audie, there has been tension in the campaign for a long time. Corey Lewandowski has been with Trump from the beginning. And he didn't have a lot of political experience, but he and Trump kind of clicked. Lewandowski led a shoestring campaign without a lot of staff or traditional fundraising or traditional organization.

And, you know, that worked well in the primaries, obviously. Trump is the presumptive nominee. But largely it worked because of the force of Trump's personality and his ability to draw those big crowds and lots of press coverage. So, you know, Trump liked this. He didn't want to run a typical campaign, and he saw his organization as efficient and lean and mean.

But eventually, as it became clear that Trump could really become the GOP nominee, he began to make newer hires in an effort to become a more traditional campaign. Some of those were more experienced operatives. And in an interview with CNN today, Corey Lewandowski acknowledged that things had been changing.

(SOUNDBITE OF ARCHIVED RECORDING)

COREY LEWANDOWSKI: As you look at how small this team has been and how close-knit this team has been, it's really important to know that there are highs and lows in every campaign. And we've been through them together. And in order to be successful, we need to continue to build that team and build those relationships with the RNC and utilize the resources that they have available to us. So that's where the campaign is going, and it's been a great privilege. And look; I wouldn't change one second.

MCCAMMON: And so, Audie, we've known that there's been a bit of a power struggle between those factions, the old and new, in the campaign for a while. We've heard from sources, though, that Trump liked that competition. He saw it as generating good ideas, and was keeping Lewandowski on in part because of his loyalty to him. But there still isn't a robust national organization and ultimately, today, we saw that Corey Lewandowski had to answer for that.

CORNISH: Now, for a long time there were significant episodes of bad press for the Trump campaign that were - that was essentially focused on Lewandowski. But you mentioned loyalty there. It means a lot to Donald Trump, right? And did that come into play here?

MCCAMMON: Well, you know, Lewandowski's been a controversial figure for months. And he's had multiple confrontations with reporters, especially - you may remember back in March he was accused by Michelle Fields, formerly of Breitbart News, of grabbing her as she tried to ask Trump a question. Lewandowski appeared to grab her on a security video, but that charge was ultimately dropped by prosecutors. And Trump stuck by him through that.

Behind the scenes, he's been seen as a divisive figure. He's had enemies inside the campaign, including some of those newer hires. And he said himself that he is an intense person. But again, Trump was very loyal to him, he was very loyal to Trump and still, from some of the things he's said today, seems to be.

CORNISH: Now, we're less than five months away from Election Day, and I know kind of in Washington that people are really talking about this. How unusual is it to make this change now, and what does it mean in terms of looking at the Trump campaign?

MCCAMMON: Well, it doesn't look good for the campaign, but I think we're seeing a lot of things leading up to this. Poll - Trump's poll numbers are dropping. And that's the thing he's been touting throughout the primary, is his strong poll numbers. He's had a couple of bad weeks. His comments about a judge of Mexican descent and his response to the Orlando shooting were widely panned, including by Republicans.

So he's really been struggling to move into general election mode. There's a pattern of Trump being in the midst of bad headlines, then saying or doing something that redirects the conversation. So, you know, more - there's a lot coming out tonight. We're going to see the latest campaign fundraising numbers when Hillary Clinton is expected to announce a large hall. And Trump has been playing catch-up in a big way.

So, you know, in terms of whether or not, though, anything changes coming forward - on the one hand, this shows us that Trump is willing to take advice from those close to him. But, you know, in the past, we've heard him talk and again about pivoting toward the general election - hasn't really done that. So now we have to see whether or not without Lewandowski's influence if Trump will evolve and if this advice is going to extend to changing his campaign style and rhetoric.

CORNISH: That's NPR's Sarah McCammon speaking to us from New York. Sarah, thanks so much.